Self-starting synchronous electric motor



May 3, 1951 J. GOTTLIEB ETAL 2,552,315

SELF-STARTING SYNCHRONOUS ELECTRIC MOTOR Filed Jan. 21, 1949 2 Sheets-Sheet l llmllln? 2.2::

1. 27 HWI INVENToRs. Q/m .10s-EPH Garn/EB.

wow/G EICKEMEYER. *y ffoy CARL WOESSNER.

ATTORNEY.

2 Sheets-Sheet 2 J. GOTTLIEB ET AL SELF-STARTING SYNCHRONOUS ELECTRIC MOTOR May 8, 1951 Filed Jan. 21, 1949 INVENTORS.

JOSEPH GOTTLIEB. LUDWIG E/C'KEMEYER. By CARL WOESSNER.

ATTORNEY Patented May 8, 1951 SELF-STARTIN G SYNCHRONOUS ELECTRIC MOTOR Joseph Gottlieb, Jersey City, Ludwig Eickemeyer,

Union, and Carl Woessner, Bloomfield, N. J., assignors to Gibraltar Manufacturing Co., Inc., Jersey City, N. J., a corporation of New Jersey Application January 21, 1949, Serial No. 71,902

7 Claims. (Cl. Hilf-278) This invention relates to a self-starting synchronous electric motor for clocks and the like.

The principal object of this invention is the provision of a self -starting synchronous motor in which a plurality of eld poles is arranged in a common circle surrounding the rotor, said field poles being all integral with a laminated field construction. In this invention the stator is laminated so that its several component parts may be stamped out of sheet metal at relatively low cost and with uniform precision. Fingers are provided on said stator and they are bent outwardly in a generally common direction to align them on a common circular line which surrounds and is concentric with the rotor. These fingers serve as the field poles of the motor and as many fingers may be provided as field poles are required.

Another object of this invention is the provision of a self-starting synchronous motor having the type of stator which is above described and which is provided With a shield between the laminations and the rotor, said shield being held in place on said laminations solely by the very fingers which constitute the field poles of the motor. The shield is also laminated so that it may be stamped out at low cost and with great, uniform precision. It has a plurality of slots and other openings formed therein to accommodate the fingers of the laminated stator. Some of these fingers are bent over upon said laminated shield to nx it in place relative both to the stator and to the rotor, and by the same token, these bent fingers also serve to unite all parts of the stator into an integral whole.

Another important object of this invention is the provision of a rotor which is so designed as to render the motor in which it is incorporated both self-starting and synchronous. This rotor is also stamped out of sheet metal for great economy in production as well 'as unusually great and uniform precision. It has a continuous rim for its self-starting properties and notches of controlled shape and depth are provided in said rim to enable the rotor to lock into cycle. The rotor is provided, in its preferred form, with twelve spokes, but six spokes or any multiple of six may be used to good advantage.

. A further object of this invention is the provision of a rotor as above described which is dished in shape to enable the flux to pass unimpeded across the center of the rotor. In this design the continuous rim lies on a given plane and the spokes and hub of the rotor are offset from said plane.

Fig. 4 is a plan View of one of the laminations which comprise the stator. Fig. 5 is a plan View of a second lamination. Fig. 6 is a plan view of a third lamination.

Fig. 7 is a plan view of a fourth lamination;v

Fig. 8 is a plan view of the shield.

Fig. 9 is a plan View of the rotor.

Fig. 10 is a diametric section therethrough on the line IU-Hl of Fig. 9.

Fig. l1 is an enlarged, fragmentary sectional` view through the stator, rotor and shield on the;

line lI-II of Fig. l.

Fig. 12 is an enlarged, fragmentary front view of the mechanism.

Fig. 13 is an enlarged, fragmentary back view thereof. Fig. 14 is a section on the line l4-l4 of Fig. 12.

Fig. 15 is a section on the line I5-I5 of Fig. 12.

Fig. 16 is a view of the lamination of Fig. 5 with its fingers bent to form field poles.

Fig. 17 is a View of the lamination of Fig. '1 showing its fingers bent to serve as field poles.

The synchronous motor shown in the drawing includes a field coil 20 which may be connected by means of conductor 2l to a source of alternating electric current. Extending through the coil is a core 23 which is magnetized in accordance with the direction of flow of the current through said coil. Laminations 24, 25, 26' and 21, shownv respectively, in Figs. 4, 5, 6 and 7, are aiiixed to core 23 by means of bolts 29. More specifically, laminations 24 and 25 are placed fiat against each other and are afxed to the one side of the core, as seen in Fig. 3, and laminations 26 and 21 are placed fiat against each other and fastened to the other side of the core as seen in said figure. Laminations 24 and 21 occupy a common plane and they are disposed in face-to-face relation with laminations 25 and 26, which also occupy a common plane.

Reference to Figs. 4 and 5 will disclose the fact that laminations 24 and 25 are provided, respectively, with upright portions 34 and 35. Lamination 24 has arms 44 and 54 formed on said upright portion and fingers 64 formed on and extending radially inwardly from said arms. Lamination 25 is provided with corresponding arms 45 and 55 on its said upright portion 35 and fingers B5, slightly longer than fingers 64, are

Laminations 26 and 21 are also provided with"` upright portions 36 and 31 respectively,..but instead of having a pair of arrnsconnectedtlereto to define a circular space therebetween, these upright portions 36 and 31 are connected to'rin'gshaped portions 15 and 11 respec-tively.d Fingers? 66 extend outwardly from, andradiall'yof, ringshaped portion 16 and iinge'rs' 61,' which are" shorter than fingers S6, projectaoutwardly' from, and radially of, ring-shaped portion 11. When laminations 2B and 21 are placed iiat upon each`V other, they coincide substantially in every respect exceptfthat;.theirffiingers are' staggered withA respent-.l 'toY each' other;y

It will hereinafter more fully appear thatzwhen the: motori'y is completely. assembled, fingers 64, 65, 66 and 6.1: are bent at'right angles to the planes onwhichitheir respective laminations extend.. When thes'efngers are sobent, it is possible to position the several laminationsin such mannerlthat the.` ring-shapedVA portions 1E and 11 of laminationslt' and 21? occupy acentral positio'nifinithefcircularfspaces denedby arms 45' and 55 of lamination.2'52`andlarms 44 and54'oi lamination 24. A substantially annular space 89 is thereby;formedbetween the arms. of lamnations 24 and 25 on the one handi and the ring-shaped portionsofilaminations andZl' on the other hand.:J It isi through this; annular space that ngers 64, 65, 65 and 61 extends when they are bentyperp'endicularlyj with` respect. to the several laminations. This annular spaceprevents any excesswes'lossfiof,t magnetic flux b'e'tween'the laminations 24-25 and laminations 2G--21- It will'belncted that laininations 24' and 25' are providedwithopenings 3|', 82' and 83 and with openings', .B5-'andi Sirrespectively: These openings register witheach'. other' when'the twolarninatioiissarefsuperposed,.one on the other. Openingsifanl53E-accommodatev one of the screws 29,', and thel other openingsf accommodate: other members: off the.' clock.mechanism to" which the motonisattached'.V More specically-they are inte'ndedztoV accoi'nmndate'y fastening members" designedftosupport-thefrnotor relative to said clock meehanisnrf. Similar openings` 81; and Si! are for-med in "lamination 2 ia'ndregistering openings 90? 91|? and! 92 are' provided. in lamination 21.

Openingszltand'iS'Z are adapted to accommodate` cation between said circular opening'. li v and'the outsideof the-shield; thereby breaking: or' interrupting;r the ring'. which, said shield describes. AY

plurality of openihgsiorholes' |63. is formed in saidishielm andi it ywill be noted that" these holes lie-fon twoicoric'entric circles which -arethemselves conc'eiitnici with? centrati opening i Blf. tieni-totl'ieseihols" |03; slots me are formed in said shield-'i termi-n ting in portions-which re'-l se'rible'theconfiguration? of holesi |0'3 and it will In addibe seen that these inner portions of slots |04 lie on a circular line which coincides with the inner circle on which some of the holes |93 are disposed. Slots |04 do not extend radially of central opening lill but instead they are virtually tangential thereto. Holes |93. and said inner portions off'slots |04 arev so arranged andI spaced as to enable them to accommodate the fingers of stator laminations 24, 25, '.26 and 21, when said fingers are bent perpendioularly with respect to said laminations.

It will be recalled that shield IIJ@ itself constitut'esf` a plurali-ty' of superposed laminations. See'Figs. 141 and-115 where the shield is shown to compriselaminations |060., Ib, Mito and mild. Lamination |0021 may be considered to be the front ylamination and lild the back lamination.

When the motor is assembled, laminated shield liloffrest's against front laminations 24 and 21 in the manner shown in Figs. 14 and l5. It will be seeh iii-Figi` 14.? that the" iingersV of laminations Zifand L1 extend through holes |615 which lie on theirlnercircle. above mentioned, and it will be uri'd'erstood` that they also extend through the innerportionsfoffslots |04. On the other hand fiiigrsiandfE of laminations ll'and 25 extend throughthefouter circle of holes |53. In the einbedlimentshow-n; these last-mentioned iingers' a'rebentat'` their outwardly extending ends'to formisubstantially` l'.-shaped portions wherein th'efo'o't portionsv of said L-shaped portions rest against'theouter.sheldlamination E tla' and the upright' portionsof said L-shaped portions are aligned with theinner circle of fingers, to wit,

253 and 'I-li'e Il-shaped' portions' of ngersv shield,holdingfsaidfshield.in position with respect toilain'in'etti'o'ns'24VJ and: 25 andV ing'ers- Strand 61 serve-'tof position said:A laminatedV shield with" re,- To the: extent'- tha-'ti these',f lL-shaped'- portions aref on the backv la'iiiination25,.they serve" to hold thetwo laminatio'ris 24 and;.25itogether asv well as'tolholdtlie spect! to? laminations- 2F' and 21;

shield'llttciigether with said laminations.

Sp'eciiicallyg.v we' have' shown fingers of stator laminati'ons12kt, 25; as being,` bent near their outer the innen'andithe' outer ring mayA be bent over the coppershielding,to'align ina commoncirclerf By bending infbetweerr both-1 rings of fingers. therfngersover'the'copper shielding, a completel unitis formedwithioutfthe'useof screwsior rivets or.: such" other' independent fastening means.'-

Aibearing'; |13 is mounted-in the openings and kH1 of: ring-shaped' portions 15 and 11 ofi laminationsn 2 6' 2:1.' f Connectedl to said! bear`` inggland; assisting in holding.saidbearinginsaid openings; isa Vlubrilatingf.:box l i2' which contains'f aiquan'tity otlub'ricatingmaterial i I3'. The bear-4 ing may be madefofl powdered metal suchi-.as the" types' known as-graphitedmetals to provide adethat it is conductive of: the lubricant contained inilubricatinglboxi I l2'.

thosefin'ge'rs whichareconnecte'd to laminations taand as serve as anchors with respect to the laminated` qii'at'e lubricatiohi not only. by" Virtue of the-l fact! the clockwork mechanism. It may have a worm 122 mounted thereon, as shown in Fig. 2 to engage a worm wheel (not shown) in the clock mechanism. When rotor 121 is mounted on said shaft |20, it lies within the circle of outwardly projecting fingers 54, 65, 53, and 61. This circle of fingers is concentric with the rotor and as has above been indicated, the fingers serve as field poles relative thereto.

It will be seen in Figs. 9 and 10 that the rotor is a wheel-shaped member' having a hub |30, a plurality of spokes |3| extending outwardly, radially from said hub, an endless rim |32 connected to the outer ends of the spokes and a plurality of notches |33 formed in said endless rim. This wheel-shaped rotor is dished tc offset its hub and spoke portions from the plane on which the endless rim is disposed. See Fig. 10. There are as many notches |33 as there are spokes 13| and these notches alternate with the spokes so that each pair of spokes has a notch between them. The spel-es are uniformly spaced from each other and the notches are uniformly spaced from each other as well as from said spokes. It will be noted in Figs. l and 1l that that portion of the rin-i in which the notches are formed extends substantially at right angles to the plane of the rim. It will further be noted that these notches are arcuate in shape. The width of the rim and the depth and width of the notches are determinative of important aspects of the performance of the motor. As has above been stated, an endless rim of appropriate width endows the motor with its self-starting properties. A suicient number of notches of appropriate depth and width enables the motor to lock into the cycle of the alternating electric current which energizes it.

The principle of operation of the above described motor is clear. The inwardly turned ngers serve as eld poles relative to the rotor and cause the rotor to rotate at a given speed which bears a direct relation to the number of cycles of the electric current to which the field coil is connected.

It will be appreciated that the foregoing is descriptive solely of a preferred form of this invention, and that form may be modied in many ways within the broad scope of the invention. Illustrative of the materials of which the abovedescribed parts may be made is the following: the rotor may be made of spring steel, the laminations may be made of cold rolled steel, and the shield may be made of copper.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent, is:

l. An electric motor of the character described comprising in combination a core, an excitation coil on said core, a rotor, a stator having a plurality of primary poles and shaded poles and consisting of a first and second half each composed of two plates, the plates of one stator half being connected to one end of said core and the plates of the other stator half to the other end of the core, the plates of said first stator half having an opening for containing the plates of said second stator half in the same plane, the primary poles being formed by a ring of teeth bent out of the plane of one plate of each stator half, and

the shaded poles being formed by a ring of teeth bent out of the plane of the other plate of each stator half in such manner that the ring of poles from said first stator half is disposed on a first cylindrical surface and the ring of poles from said s cond stator half is disposed on a second cylindrical surface which is embraced within said first cylindrical surface.

2. A motor as set forth in claim l and comprising a common laminated ring-shaped shortcircuiting element surrounding the teeth of the shaded poles.

3. A motor as set forth in claim 2 and in which the teeth formed from the plate of each stator half remote from said short-circuiting element is secured thereto thereby binding both pairs of stator plates to said element.

4. A motor as set forth in claim 3 and in which at least one stator half is secured to the shortcircuiting element by having the free ends of its pole teeth bent L-shaped with the foot portions resting against the outer short-circuiting lamination and the upright portions in the cylindrical surface of the other pole ring.

5. A motor as set forth in claim 1 and comprising a common laminated short-circuiting element surrounding the teeth of the shaded poles, said element being ring-shaped, having a substantially circular opening formed therein and a radially extending slot formed in said element to communicate between said opening and the outer edge of the element, a rst and second ring of spaced slots formed in said element, said rings being concentric with one another and with said circular opening, no two of said slots lying along the same radius, said shaded pole teeth passing through said slots.

6. A motor as set forth in claim 5 and in which a first group of openings is formed in said shortcircuiting element aligned with the outer ring of slots and located in alternating spaced relationship therewith, said openings having radial slots connecting each respectively with the outer edge of said laminated element, and a second group of openings is formed in said laminated element aligned with the inner ring of slots and located in alternating spaced relationship therewith, said second group of openings having slots substantially tangential to said circular opening connecting each respectively with the outer edge of said element, all of said slots and openings lying on independent radii of said laminated element.

7. A motor as set forth in claim 6 and in which said primary pole teeth pass through said first and second groups of openings.

file of this patent:

UNITED STATES PATENTS Number Name Date 2,015,042 Reinhardt et al. Sept. 17, 1935 2,018,677 Kohlhagen Oct. 29, 1935 2,212,782 Lauifer Aug. 27, 1940 

